Heater



Nov. 22, 1938. w M, MYLER, JR 2,137,581

` HEATER Filed Nov. l, 1937 Snventor Gttorneg Patented Nov. 22, 1938 UNITED STATES HEATER William M. Myler, Jr.,

Columbus, Ohio, assignor to Surface Combustion Corporation, Toledo,

Ohio,

a corporation of New York Application November 1, 1937, Serial No. 172,179

1 Claim.

'I'his invention relates to improvements in space heaters of the type embodying a gas-fired radiator,

a fan for blowing air past the radiator whereby to heat the air, a room thermostat for start- 5 ing and stopping the motor which drives the fan and means for shutting off the burner when there is no call for heat. In space heaters of this type and more particularly in so-called unit heaters adapted to be hung near the ceiling of 10 the enclosure to be heated, the radiator is usually made of relatively thin sheet metal and is, therefore, relatively easily damaged by overheating. The most usual cause of overheating is failure of the burner gas valve to close when the fan stops running. such failure usually being due to the valve having become dirty or gummy from the fuel gas. Various schemes have been proposed to overcome the danger of the main gas valve failing to close when it should, but all such schemes 20 of which I am aware have proceeded on the assumption that it was absolutely necessary to shut off the gas to the burner.

The object of the present invention is to provide a relatively simple and practical way of over- 25 coming the danger of damage to the radiator in case the burner gas valve fails to close the way it should. According to the present invention, no special means are provided to insure that the supply of gas to the burner shall be cut off in case the main gas valve fails to function normally. Briefly stated, what I do is to provide means, independent of the room thermostat, for causing the fan to operate in case the burner gas valve fails to close the way it should. By thus causing the fan to operate, the flow of air produced by the fan will keep the radiator suiciently cool to prevent its being damaged. Moreover, the means which I employ is such as to cause the fan to start and stop periodically, thus calling attention to the fact that the heater is not operating in a 'normal way.

For a more complete understanding of the invention reference is made to the detailed description taken in connection with the accompanying drawing, wherein the preferred form of the invention is shown.

Fig. 1 is a side elevation of a type of space heater with which the invention has special utility, 5o parts of the heater being in section and certain other parts being more or less diagrammaticallyy illustrated;

Fig. 2 is a fragmentary sectional view of line 2-2 of Flg. 1, and 55 Fig. 3 is a diagram illustrating how the invention is applied to a heater of the type shown in Fig. 1.

The space heater is shown as comprising a combustion chamber IIl whose top side is in open communication with a plurality of radiator'tubes II of relatively thin sheet metal, the tubes being arranged in laterally spaced relation to form air passages therebetween. The upper ends of said tubes open into an exhaust chamber I2 from which leads an exhaust flue I3 for conducting the gases of combustion to a point outside of the enclosure where the heater is located, said chamber also being shown as having anopening I4 open to the atmosphere of the enclosure with a result that the chamber also serves as a draft diverter. In the combustion chamber I is a gas burner I5 to which the flow of gas is controlled by a gas valve I6 in a gas supply I'I. The pilot for the burner is indicated at I'. I8 indicates a fan for blowing air past the radiator tubes whereby to heat the air passing therebetween; and I9 indicates adjustable air deflectors at the air exit side of the radiator. The fan is driven by a motor 20 supported on a bracket 2I secured to the framework of the heater.

At the discharge side of the fan is hung a freely movable vane 23 which, when the fan is running, is held by the force of the air from the fan in such position that it will cause a mechanism (not shown in Fig. 1) to open the gas valve I6 with resultant flow of fuel to the burner.

A unit heater of the type described is well known in the art and per se forms no part of the present invention. It remains to be said that a room thermostat controls the application of power to the fan motor.

One of the essential elements of the present invention is a safety thermostat which is so 1ocated as to be responsive to the temperature of a heated part of the heater itself. In Fig. 1, the most convenient and preferred position is indicated by the rectangle 25', this position being adjacent to the wall III of the combustion chamber I0. As will more fully appear hereinafter, the function of said thermostat is to cause the fan I8 to run for a period and then stop in case the gas burner does not shut oil when the room thermostat moves to no-call-for-heat position. The said safety thermostat is indicated at 25 in Fig. 3 and, for purposes of illustration rather than limitation, has been shown as comprising a bimetal disc supported by spacer brackets 39 secured to the said wall I0'. Thermostats of this type operate with a snap action and are well known in the art.

In the layout of the controlling mechanism shown in Fig. 3 the mechanism for opening the gas valve I5 is shown as including a solenoid 30 in a power circuit 3l which also includes two switches 23' and 32, the s'witch 23' being operatively connected to the vane 23 for operation thereby. In the position of the parts shown in Fig. 8, the gas valve is supposed to be stuck open and not positively held open by power applied to the solenoid. The normal power circuit for the fan motor 20 is indicated at 33. In this circuit is a switch 34 which is operatively connected to a temperature controller or room thermostat 35 in such a way that when the controller calls for heat the switch will be moved to closed position and thereby admit power to the fan motor 20. 35 indicates another power circuit which shunts out Ythe switch 34. In this circuit 36 is a switch 31 shown as closed. 'Ihis switch 31 is operatively connected to the safety thermostat 25 as by a stem 33. When the switch 31 is closed, it means that the safety thermostat 25 has been actuated due to the excessive temperature prevailing at the combustion chamber wall ill'.

It will now be seen that when the switch 31 is closed, power flows to the fan motor 20 which is the same thing as saying that the fan I8 is running. Although when the fan is running the vane 23 operates to close the switch 23', nevertheless power is not applied to the solenoid 30 by reason of the fact that the switch 32 is open. 'Ihis switch 32 is shown as mounted on the same stem 33 as the switch 31. After the fan I8 has been running for a relatively short period, the air from the fan will cool the wall I0' of the combustion chamber to such degree that the thermostat 25 will snap back into its normal position with consequent opening of the switch 31 and closing of the switch 32. If the gas valve i6 still remains in stuck open position and the room thermostat 35 does not close the switch 34 in the meantime, the wall I0' will again become sumciently hot to cause the thermostat 25 to operate. This periodic starting and stopping of the fan by the safety thermostat 25 will, of course, indicate that something is wrong with the normal operation of the heater.

It will be understood from the foregoing that the safety thermostat 25 will remain in normally inactive position as long as the combustion chamber wall Il' does not exceed a predetermined maximum and that after it has been actuated, it will remain in actuated position long enough to permit the temperature of the wall to reach a predetermined minimum which may be the maximum temperature that prevails under normal operating conditions.

Although it is preferred that the switch 32 be provided for preventing the application of power to the solenoid 30 when the safety thermostat 25 is actuated to close the switch 31 and thereby to start the fan going, nevertheless it is within the spirit of the invention to omit the switch 32 and make the power line 3l continuous except for the switch 23' which is actuated by the vane 23. In such event power would, of course, be applied to the solenoid 30 when the fan is running with the result that the valve I6 would not be free .to close. However, in such case, if the condition of the valve i6 is such that it would normally close when power was not applied to the solenoid, it would have an opportunity of closing when the safety thermostat 25 moved back to inactive position.

I also wish to state that although the invention has been shown in connection with electric power means for opening the gas valve, nevertheless it is equally adapted for use in connection with space heaters having means other than electrical means, for example gas operated means, for opening the gas valve. It is, therefore, to be understood that no limitations are intended except as may be expressed in the appended claim. I

What I claim is: In apparatus comprising a fuel-fired radiator,

' and a fan for causing air to flow over the radiator whereby to abstract heat therefrom, and a main control switch for starting and stopping the fan, and a fuel supply valve for the radiator, said valve being normally closed when the fan is not running, and means dependent on the operation of the fan for opening the fuel valve, the combination of means for preventing the radiator from overheating in case the fuel valve sticks open after the fan has been shut oiI by said control switch, said means comprising means responsive to an abnormal heat condition at the radiator for automatically re-applying power to the fan whereby to cause the air from the fan to abstract heat from the radiator as long as said abnormal heat condition exists.

WILLIAM M. MYLER, Jn. 

